miniShell

Minishell

Minishell is a simplified shell program that emulates a Unix-like shell environment. It is built using C and provides a basic command line interface (CLI) where users can interact with the system, execute commands, and manage environment variables. This project also includes implementations of several built-in commands such as cd, echo, env, and more.

Features

Command Parsing and Execution

• Command Line Parsing: The shell parses user input and supports command execution by interpreting the provided commands and arguments.
• Tokenization: Commands are tokenized for proper interpretation, including handling of special characters and operators.
• Command Expansion: Supports expanding environment variables and removing quotes from the input commands.
• Builtin Command Support: Includes built-in support for common shell commands such as:
  • cd: Change the current directory.
  • echo: Display a line of text.
  • env: Print environment variables.
  • export: Set environment variables.
  • unset: Unset environment variables.
  • pwd: Print the current working directory.
  • exit: Exit the shell.
• Custom Prompt: Displays the current user, directory, and exit status in the prompt, dynamically updating based on environment variables and user input.

Signal Handling

• Signal Management: The shell can handle various signals like SIGINT (Ctrl+C) and SIGQUIT to gracefully exit or manage interruptions. The signal handling ensures the shell remains stable during user interactions.
• Custom Signal Handlers: Custom handlers manage shell behavior during different states:
  • Interactive mode: Default mode during command entry.
  • Heredoc mode: Special handling for commands involving here-documents (<<).
  • Child process mode: Handling signals within child processes.

Heredoc Support

• Heredoc Feature: Implements support for the << operator to allow multiple-line inputs, which is particularly useful for feeding input to commands interactively.

Environment Variable Management

• Environment List: The shell maintains a list of environment variables that can be modified using built-in commands like export and unset.
• Dynamic Environment: Supports dynamically updating the environment, including handling variable expansions within commands.

Execution of External Commands

• External Commands: In addition to built-in commands, the shell supports executing external binaries found in the system's PATH variable.

Error Handling

• Argument Checking: The shell checks for valid arguments before executing commands and provides informative error messages for invalid commands or arguments.
• Memory Management: Proper memory handling and cleanup to prevent memory leaks and ensure smooth operation.

Readline Integration

• History Support: Maintains command history using the readline library, allowing users to scroll through previously executed commands using the up and down arrow keys.
• Custom Readline Prompt: The prompt is customized to display user-specific information and can be dynamically updated.

Compilation and Makefile

• Makefile Support: The project comes with a Makefile to simplify the compilation process. The Makefile includes the following targets:
  • all: Compiles the project and builds the minishell executable.
  • clean: Removes object files.
  • fclean: Cleans up object files and the compiled binary.
  • re: Recompiles the project from scratch.
  • run: Runs the shell with memory checking via valgrind.

Compile

1.Navigate to the project directory.

cd minishell

Compile the project.

make

Usage

Once the project is compiled, run the shell by executing:

./minishell

Use the shell as you would with any other Unix-like shell by entering commands and pressing Enter.

Example:

$ pwd
/home/user/minishell
$ cd ..
$ echo "Hello, World!"
Hello, World!

To exit the shell, use the exit command:

$ exit

Libraries

• Readline: This project uses the readline library for handling command-line input and history.
• Libft: The project relies on libft, a custom C library for utility functions such as memory management, string handling, and more.